What the Chief is alluding to, here, and for those of us who have had to deal with them, the only thing on earth worse than a Lucas electrical system is whatever - in - 'ell you call the 'Marialli' crap that Fiat has been known to use.
Actually the light switch is the least of your problems. The wiper switch is going to be a challenge, and wiring will depend on what kind of motor you have now.
Last, I would certainly NOT start with a factory harness if that is what you are determined to do.
Why in 'ell am I up at 4:45AM. I can't freekin sleep, that's why
